Telecommunications – Transmitter and receiver at separate stations – Frequency or phase modulation
Reexamination Certificate
1998-01-26
2002-07-02
Maung, Nay (Department: 2681)
Telecommunications
Transmitter and receiver at separate stations
Frequency or phase modulation
C455S039000, C455S186100
Reexamination Certificate
active
06415135
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to the transfer of files from a transmitting device to a receiving device in a digital telecommunication system in general and to a method of using a file mapping procedure mentioned but not strictly defined in the standard ETS 300 401 to transfer information associated with the files to be transferred.
BACKGROUND OF THE INVENTION
Digital Audio Broadcasting (DAB) is a new transmission system, which is expected in the long run to replace the broadcasting systems based on analog amplitude and frequency modulation, which are presently used in radio broadcasting to masses of people. The main features of the definitions concerning the DAB system are presented in the standard ETS 300 401 of the European Broadcasting Union (EBU) and the European Telecommunications Standards Institute (ETSI). In order to shed light on the background of the present invention, the features of the DAB system which are essential with regard to the invention will be presented briefly in the following.
One signal stream transmitted by a transmitting device according to the standard forms a DAB ensemble, which can contain many services (
2
,
3
,
4
) as shown in FIG.
1
. From the user's point of view, each service corresponds to one radio channel of the present systems, and it consists of one or more service components
5
,
6
,
7
,
8
,
9
,
10
. A single service component
5
can contain, for example, the audio part offered by the service
2
, such as music, or a data part associated with it, such as the lyrics of the song being played, or other information associated with the service
2
. One service component
6
can be a part of more than one service
2
,
4
. The service component, which is the most essential with regard to the service is called the primary service component, and the other service components which belong to the service are called secondary service components. The primary service component is often the audio part offered by the service, but it can also be a data part. The service can also contain many audio parts as service components.
FIG. 1
shows the connection between each service (such as Radio A;
2
) and its primary service component (in this case Audio;
5
) with a thick line.
The information to be transmitted over the radio interface of the DAB system from the transmitter to the receiver is divided into three channels according to its purpose, as shown in FIG.
2
. The channels are: Main Service Channel (MSC)
11
, Fast Information Channel (FIC)
12
and Synchronization Channel
13
. The service components
5
to
10
mentioned above are transmitted in the service channel
11
, which is further divided into separate convolution-coded sub-channels (
11
a
,
11
b
,
11
c
,
11
d
,
11
e
in FIG.
1
). Each sub-channel can transmit one or more service components. The mutual order of the service components and the sub-channels is called multiplex configuration. The fast information channel
12
contains the multiplex configuration information (MCI) in particular, but it can also be used to transmit other information quickly from the transmitter to the receiver. The synchronization channel
13
is used to control the transmission and reception operation of the system, such as the synchronization of the transmission frames.
A DAB transmission consists of parts that are positioned hierarchically. The uppermost level of hierarchy is the transmission frame
14
according to
FIG. 2
, which contains a separate portion for each of the three channels
11
,
12
,
13
. Only the portion of the service channel
11
is essential with regard to the invention, and it will be described in more detail in the following.
The portion of the service channel of the transmission frame consists of Common Interleaved Frames (CIF)
15
, of which there are one or four, depending on the type of the transmission frame
14
, and each of which contains 55296 bits. Each common interleaved frame
15
can be further divided into Capacity Units (CU), not shown in the figure, of which there are 864, each with a length of 64 bits. The capacity units are in the common interleaved frame
15
, numbered consecutively so that the number or address of the first capacity unit is 0 and that of the last one is 863. The relation of the above mentioned sub-channels to the capacity units is such that one subchannel comprises an integer number of consecutive capacity units. One capacity unit can belong to one sub-channel only. If the sub-channels do not use all the capacity units of the common interleaved frame
15
, the remaining capacity units are filled with padding bits, which are zeros.
Two transport modes have been defined for the service channel
11
, namely the stream mode and the packet mode. Because the invention relates only to the use of the packet mode, only that will be described in the following.
When information to be transmitted in the service channel is formed and processed in the transmission equipment, it is handled as so called logical frames. One logical frame contains the amount of information associated with one service component, the presentation of which to the user takes 24 milliseconds. The number of bits contained by it depends on at which point of the transmission coding the logical frame is handled, and what is the bit rate associated with the subchannel used to transmit it. The information contained by each logical frame is, in the case of the packet mode, further grouped into packets, an integer number of which are incorporated in the logical frame. The length of the packets is 24, 48, 72 or 96 bytes, or 192, 384, 576 or 768 bits. Each packet comprises a packet header, which includes, among other things, a 10-bit address indicating which service component the information contained by the packet is associated with. In addition, each packet comprises a data field and a checksum field. All packets containing information relating to the same service component have the same address. The above mentioned multiplex configuration information MCI transmitted by the fast information channel contain links by which the addresses of the packets are associated with the corresponding service components.
For transmission, the packets are arranged in a manner presented in the standard ETS 300 401 to the above mentioned sub-channels. Each sub-channel can contain packets, which have the same or a different address. Within the service channel, packets with different addresses can be transmitted in any order, but the mutual order of packets with the same address, which refer to the same service component, must be retained.
Information associated with the service components is related to the packets mentioned above in a manner such that data groups
16
according to
FIG. 3
are formed thereof, and the data groups
16
are divided into parts for transmission, which parts are placed into packets
17
,
18
,
19
, with the same address. It is for this reason that the mutual order of packets with the same address must be maintained: if the order is changed, the contents of the data group transmitted by the packets can no longer be reconstructed correctly. The first packet
17
transmitting the data group
16
contains an address (not shown) in its header
17
a
, which address is here denoted by j. Its header
17
a
also contains the information that it is the first packet of data group
17
, which means that the so called First-bit of the header
17
a
is 1, and the so called Last-bit is 0. All the following packets
18
,
19
, which transmit the same data group
17
, contain the same address j (not in the Figure) in their header
18
a
,
19
a
. In the header
19
a
of the last packet
19
, the First-bit is 0 and the Last-bit is 1. In the header
18
a
of the packets
18
in between, both the First and Last bits are 0.
The internal construction of the data group
16
is of no importance with regard to packet switching, but it is of importance with regard to the invention, and so it is described in the following with reference to FIG.
4
. At the beginning of the data
Maung Nay
Oy Nokia Ab
Perman & Green LLP
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